When the lock has finished you will have a chance to rate it out of 5 stars. When more than 5 ratings have been gained for the lock and keyholder the average rating will be available for others to see. The keyholder will see the average rating on each of their locks and when lockees load the lock they will see the average rating for the lock, and the average rating for the keyholder.
Keyholders can also rate users that have completed or abandoned their locks.
Once a rating is set you only have a short period of time to change it if needed.